The body generates electrical signals or impulses that produce contraction of tissue fibers. These electrical impulses are commonly referred to as myoelectric signals or MES. Myoelectric signals have frequencies ranging from a few hertz to about 300 Hz, and voltages ranging from approximately 10 microvolts to 1 millivolt. MES is most often associated with skeletal muscles that control voluntary movements, although MES also includes electrical signals within nerves or central nervous system tissue.
A variety of devices are available for acquisition and processing of myoelectric signals. These electrical signals are often used as instruction signals for control devices. As an example, acquisition and processing of myoelectric signals has been used to provide instruction signals to control systems that control mechanical movements of a prosthetic limb of its user. Or, the controller may direct other devices to provide electrical signals to muscles and/or nerves where the body is no longer able to generate an appropriate electronic signal.
These instruction signals are first generated by contraction of the user's own remaining muscles and are acquired from these muscles through a plurality of electrodes. The electrodes may be placed either on the external surface of the skin, or may be surgically implanted. A myoelectrically-controlled prosthesis uses these instruction signals (the electrical impulses) to operate a motor in a mechanical hand, work hook, or elbow, for example.
While existing devices, systems, and methods can provide adequate acquisition and processing of myoelectric signals, many limitations and issues still remain. For example, existing acquisition and processing systems are often external the body and therefore create a degree of nuisance and can degrade the quality of life of the user.
It is time that devices, systems, and methods for acquisition and processing of myoelectric signals address not only specific prosthetic or therapeutic objections, but also address the quality of life issues of prosthetic users.